Automobile manufacturers are developing electric vehicles (including hybrid vehicles) to reduce exhaust emissions from vehicles. Such a vehicle uses a motor as a drive source. The motor is powered by a battery. Whenever the state of charge of the battery becomes low, the user of the electric vehicle must charge the battery with a charger that is installed in a household or a charging station. Japanese Laid-Open Patent Publication No. 9-161898 describes a charging system for an electric vehicle that is easy to use. This charging system includes an inlet, or power receiving connector, which is arranged in the vehicle and connected to a power feeding connector (power feeding plug). The power feeding plug is connected to a household outlet for a commercial power supply. When the user is at home, the user connects the power feeding plug to the inlet of the parked vehicle to charge the vehicle battery with commercial power.
To prevent separation of the power feeding plug from the inlet, a locking device is used to hold the power feeding plug on the inlet. One example of such a locking device includes a hook, which is arranged on the power feeding plug, and a catch, which is arranged on the inlet. The hook engages the catch to lock the power feeding plug to the inlet. This prevents separation of the power feeding plug from the inlet. To disconnect the power feeding plug from the inlet, the hook is separated and disengaged from the catch. This unlocks the power feeding plug from the inlet.
Although fast charging technology is being developed for electric vehicles, the time required to charge the battery of an electric vehicle is still much longer than that required to refuel a gasoline engine vehicle. Further, quick chargers are still rarely installed in normal households. Thus, when a user charges the battery of an electric vehicle at home without using a quick charger, the user plugs the power feeding connector to a household outlet. In this case, the vehicle would be left unattended over a long period of time. However, someone may disconnect the power feeding plug from the vehicle and connect the power feeding plug to another vehicle to steal electricity. Otherwise, the power feeding plug itself may be stolen.
A locking device has thus been developed to prohibit unauthorized disconnection of the power feeding plug from the inlet. One example of such a locking device includes a lock bar, which is driven by a motor. In a state in which the hook of the power feeding plug is engaged with the catch of the inlet, the lock bar fastens the hook at a lock position and restricts movement of the hook. When the lock bar is in such a locked state, the power feeding plug cannot be disconnected from the inlet. To disconnect the power feeding plug from the inlet, the lock bar is moved to an unlock position to permit movement of the hook.